diff --git a/package.json b/package.json
index 0c1f23da..4b592a5c 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,8 @@
   },
   "dependencies": {
     "bn.js": "4.11.6",
-    "elliptic": "6.4.0"
+    "elliptic": "6.4.0",
+    "hmac-drbg": "^1.0.0"
   },
   "optionalDependencies": {
     "bcoin-native": "0.0.16",